The human kidney performs vital functions for the body including filtration of the blood and the concentration of urine. Damage to the functional units of the kidney, referred to as nephrons, are ultimately irreversible and are caused by a variety of kidney diseases. This fact coupled with the estimation that kidney disease affects one in 10 people and is projected to increase highlights the necessity for curative treatments. Currently the only cure for renal disease is transplantation of donor-recipient matched kidney, however the demand for matched donors has and will continue to chronically outstrip supply. Thus there is an urgent need for the generation of patient-matched transplantable kidneys. Advancements in developmental and stem cell biology enable the scientific community to test approaches that will instruct pluripotent stem cells to kidney formation, however there are still significant gaps in our understanding of how to instruct the full complement of specific kidney cell fates in an organized three-dimensional structure. Thus a top priority of the field is to investigate novel biological mechanisms required for kidney formation, recapitulate these processes in vitro, and test the sufficiency of these processes to enhance state-of-the-art kidney organoid engineering methods. The initial goal of this application is to create a highly detailed map of human kidney development by identifying the transcriptional signatures of nephron progenitor populations in human fetal kidneys. These approaches will be optimized in and compared to mouse datasets to enable meaningful comparisons between species. These data will inform hypothesis-driven experimentation into elucidating required genetic regulatory elements necessary for in vitro nephrogenesis. In parallel, this project will test biophysical parameters for sufficiency to continuously expand in vitro nephrogenesis that will enable organ engineering approaches.